Watch crown



pril 9, 1968 GROHQSKI ET AL WATCH CROWN 5 h ts-Sheet 2 Filed y 1. 1966 .4 A r ran/van- 3 Sheets-Sheet r WATCH CROWN R. J. GROHOSKI ET AL pril 9, 1968 Filed July 1, 1966 '1. 125 YMOND J. 690mm 850? u: anvur Arron/Wm United States Patent Oflice 3,376,701 WATCH CROWN Raymond J. Grohosld and Robert W. Denley, Watertown,

Conn., assignors to the United States Time Corporation, Waterbury, Conn, a corporation of Connecticut Filed July 1, 1966, Ser. No. 562,294 Claims. (Cl. 58-90) ABSTRACT OF THE DISCLOSURE A crown for a watch is adapted to fit over a tubular pendant. The crown prevents leakage of water into the Watch. The crown construction includes elastic annular gasket and a hard annular self-lubricating ring, both of which fit around the pendant.

The present invention relates to watches and more particularly to a waterproof watch crown.

The increased attention that the waters of the world are now receiving, for leisure activities and economic exploitation, has created a demand for a truly waterproof watch. The life of a deep sea diver may depend upon the accuracy and functioning of his watch, which he uses to time the duration of his dive.

Extensive testing, in the laboratory as well as in practical use, has shown that the present so-called deep sea watches often fail to exclude water from the watch works. This failure is not due to the watch case, but to its crown, even when the crown is of the specially constructed deep sea type.

The cause of these failures was diflicult to ascertain. Watches were tested under pressures equivalent to water pressure at six hundred feet and the watches worked. Surprisingly, the same watches leaked when they were tested by swimming around in a shallow pool at a depth of three or four feet. The watches could then be emptied of water and re-tested at a pressure equivalent to six hundred feet and again not leak. In contrast, other watches would leak in use at great depths and not leak in shallow water.

The requirement of water-tightness is essential to a crown for a waterproof Watch intended for use underwater. However, the crown must also meet the general requirements for a quality watch crown, namely that it does not wear out the tubular neck (case pendant) when it turns; that it is relatively easy to turn; that the crown itself is not readily worn out by its turning on its pendant; and that the crown may be readily replaceable on its stem without requiring the use of special tools. In addition, preferably the crown should be relatively inexpensive. Its materials should not be costly and it should be simple to manufacture, in that it is adapted for high-speed production with high accuracy of its parts.

It is the objective of the present invention to provide a waterproof crown construction which prevents entry of water into a watch when the watch is worn under shallow or deep water, which is relatively inexpensive, and which is easily replaceable on its stem.

In accordance with the present invention, a crown is provided having an internal cavity which fits over its case pendant (the tubular neck portion of the case). An elastic gasket, preferably of rubber, is tightly wedged between the crown and the pendant to provide sealing. The gasket may be, for example, round (an O ring), square or D shaped.

A hard self-lubricating ring is provided within the cavity, either above or below the gasket, to prevent sidewise motion of the crown. A metal washer is staked on the bottom of the crown to retain the gasket and the ring in their positions.

3,376,701 Patented Apr. 9, 1968 It has been found that previous crowns permitted leakage because their gaskets were unsealed or unseated by side-wise pressures on the crown. Such pressures are prevented from affecting the sealing of the crown of the present invention because of its self-lubricating ring.

Other objectives will be apparent from the detailed description of the preferred embodiment given below, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side vertical sectional view of an embodiment of the present invention; and

FIGS. 2-9 are side sectional views of other embodiments of the present invention.

The waterproof crown construction shown in FIG. 1 includes a crown body 1. The crown body, preferably constructed of brass or stainless steel, has teeth 2 to enable the fingers to grip the crown for turning. The crown is turned when the watch is set in either a mechanical or electric watch, and when the latch is wound in a mechanical watch. The crown body has a tubular cavity 3 forming a pedestal (center body) 4. The pedestal 4 has internal screw threads 5 which are screwed onto the external screw threads 6 of the winding stem 7. The winding stem is connected to gears which in a mechanical watch in one position, usually toward the case body, winds the mainspring. In its other position, usually pulled out from the case body, the crown sets the hands. In an electric watch the crown usually is pulled out from the case body to set the hands.

The cavity 3 of the crown body 1 fits over the case pendant 8. The case pendant 8 is a tubular neck which is integral with a portion of the watch case, usually the bezel 30. The cavity 3 has an enlarged lower portion 9 which is adapted for the insertion of the crown members utilized to prevent entry of water from outside of the crown and through the crown body and the internal opening of the case pendant and into the watch. A hard selflubricating ring 10, preferably of plastic, is positioned at the top of cavity portion 9. The plastic ring may be relatively inexpensively molded with great accuracy by conventional injection molding techniques. The plastic is a selflubricating bearing material, preferably an acetal copolymer. Suitable acetal copolymers include Celcon brand, manufactured by Celanese Corporation, or Delrin brand, manufactured by Du Pont. Other suitable plastics are formed by the mixture of Teflon, Du Ponts brand of polytetrafluoroethylene, with polycarbonates or acetal copolymers. In addition, molybdenum-disulfide may be included in the plastic mixture to increase lubricity and reduce wear. The plastic ring has considerable compressive strength so it prevents side-wise motion of the crown body 1 under side-wise thrusts, such as is shown by arrow A. In addition, it prevents side-wise motion of the crown body 1 under those thrusts having side-wise components similar to the motion in the direction of arrow A.

A gasket 11 is positioned beneath the plastic ring 10 and within the lower portion 9 of cavity 3. This gasket 11, in the embodiment of FIG. 1, is originally an O ring which is circular in cross section prior to the insertion of the case pendant within the cavity 3 of the crown body 1. Preferably, the O ring is made of rubber. The rubber preferably is of the type which is resistant to salt water and may be artificial rubber. The O ring is sufiiciently large so that it is compressed and distorted when the crown is positioned over the case pendant. The O ring prevents water from seeping between the crown body and the case pendant.

A metal retaining washer 12 is staked or glued within a ledge portion 13 of the crown body 1. The metal retaining washer is used to retain the O ring gasket 11 and 0 the plastic ring 10 within the crown body. It is not possible to simply extend the metal retaining washer 13 as far as the case pendant and to utilize that washer to prevent side-wise thrust because it would rapidly wear out the case pendant when the crown is turned.

As a specific example, a crown having an internal diameter of 0.133 inch at its lower cavity section was constructed in accordance with the embodiment of FIG. 1. A plastic ring having an internal diameter of 0.099 inch and an external diameter of 0.135 inch and an O ring rubber gasket having an external diameter of 0.143 inch and an internal diameter of 0.094 inch (all dimensions prior to insertion into the cavity) were inserted in the crowns cavity. This watch would not leak under actual diving conditions and when tested at a pressure of 267 lbs. per square inch under static conditions.

The embodiments shown in FIGS. 29 are similar in most of their parts to the embodiment of FIG. 1 and the parts labeled with the same numerals perform the same function in the described embodiments.

In the embodiment of FIG. 2 the gasket 14 fills the entire space between the metal retaining washer 13 and the plastic ring 10. In this embodiment the gasket 14 is an annular ring of a substantially square cross section before the case pendant is pushed within the crown. The gasket 14 is larger than the available space between the crown and the case pendant so that it becomes under pressure when the case pendant is fitted within the crown.

In the embodiment shown in FIG. 3 the gasket 15 is a ring, preferably of rubber, of a D shape, in cross section prior to its being placed under pressure when the case pendant is fitted within the crown.

In FIG. 4 the annular rubber gasket 16 is, like the gasket 15 of FIG. 3, of a D shape. However, gasket 16 is relatively elongated in shape compared to its height.

In the crown shown in FIG. the annular gasket 17 is in the form of a trapezoid in cross section. The crown of FIG. 6 has an annular gasket 18 having a cross section of an elongated rounded shape, similar in crosssection to an egg shape.

In the crown of FIG. 7 the rubber gasket -19 is in the form of a fiat annular ring, i.e., shaped like a washer, prior to insertion of the case pendant within its hole. The hole within the gasket 19 is slightly smaller than the outer diameter of the case pendant 8. When the case pendant is forced up through this hole it bends the inside portion of gasket 19 upward into an open portion 20 of plastic ring The ring 10 has an inverted L shape. The outer portion of gasket 19 is held firmly between the bottom of ring 10 and the top of washer 12. The inner portion of gasket 18 is loose within opening 20.

In the embodiment of FIG. 8 a gasket 21 is held, at its outer periphery, between inverted L shaped plastic ring 10' and the retainer washer 12. The gasket 21 is relatively thick compared to gasket 19 of FIG. 7. The inner hole of flat rubber annular gasket 21 is smaller than the outer diameter of case pendant 8 so that its inner portion is forced upward and squeezed between the case pendant 8 and the inner lower wall 22 of plastic ring 10.

In all the embodiments a lubricating material, for example, a suitable lubricating oil, may be placed on the crown pendant prior to its being joined with the crown body, so that :the gasket may more readily be turnable in relationship to the case pendant.

Modifications may readily be made within the scope of the present invention as specified in the subjoined claims. For example, the crown body and the winding stem may be made of an integral pieceof metal or of a hard plastic. The plastic ring may be replaced by other relatively hard self-lubricating materials such as an artificial jewel or an oil impregnated porous metal made from sintered metal powder. As another example, in each of the embodiments of FIGS. 1-6 the position of the plastic ring and the gasket may be interchanged. The plastic ring may be placed next to the metal retaining washer and the gasket positioned on top of the plastic ring. This interchange is shown in FIG. 9, which is the same as the construction of FIG. 1 except that the position of the ring and the'gasket are interchanged and a staking lip 23 is used in place of washer 12.

We claim:

1. A waterproof watch crown comprising a crown body having an internal tubular cavity, said crown body being adapted to fit over a watch case tubular pendant; a pedestal portion affixed to said crown body within said cavity and adapted to fit within the said case pendant and to be attached to the winding stem of a watch; a hard ring of self-lubricating material within said crown cavity and adapted to be substantially pressed between said crown and said pendant to prevent side-wise motion of said crown; an elastic gasket within said cavity adapted to be compressed between said crown and said pendant; and means on said crown to partially cover said cavity and retain said ring and said gasket within said cavity.

2. A watch crown as in claim 1 wherein the hard ring is a plastic material.

3. A watch crown as in claim 2 wherein the plastic ring is of an acetal copolymer resin.

4. A watch crown as in claim 1 wherein the hard ring is an oil impregnated sintered metal.

5. A watch crown as in claim 1 wherein the crown body has a plurality of external teeth.

6. A watch crown as in claim 1 wherein the gasket is an O ring which is substantially circular in cross section prior to its compression.

7. A watch crown as in claim '1 wherein the gasket is a ring which is substantially square in cross-section prior to its compression.

8. A watch crown as in claim 1 wherein the gasket is a ring which is substantially D shaped in cross-section prior to its compression.

9. A watch crown as in claim 1 wherein the gasket is in the form of a flat annular ring prior to its compression.

10. A watch as in claim 9 wherein the hard ring is of the form of an inverted L.

11. A watch crown as in claim 1 wherein the hard ring is positioned above the gasket and the gasket is positioned next to the covering means.

12. A watch crown as in claim 1 wherein the hard ring is positioned next to the covering means and the gasket is positioned above the said ring.

13. A watch crown as in claim 1 and having internal screw threads within its pedestal portion adapted to screw onto a winding stem.

14. A watch crown as in claim 1 wherein the means on the crown to partially cover said cavity is a metal washer afiixed to the crown.

15. A watch crown as in claim 1 wherein the means on the crown to partially cover said cavity is a staked lip on the crown.

1 References Cited UNITED STATES PATENTS 2,771,734 11/1956 Morf 58-90 2,779,153 1/1957 Soquel 58-90 2,844,421 7/ 1958 Hayman 277-188 2,862,736 12/ 1958 Russell 277188 2,912,819 11/ 1959 Waldman 58-90 2,973,978 3/1961. Oppenheim 277-188 FOREIGN PATENTS 316,459 11/1956 Switzerland.

327,358 3/ 1958 Switzerland.

331,280 10/ 1958 Switzerland. 1,092,189 4/ 1955 France.

RICHARD B. WILKINSON, Primary Examiner. S. A. WAL, M. LORCH, Assistant Examiners. 

